What Causes Painful Blue And Black Blotches On The Left Arm?

MY DAUGHTER IN LAW WHO IS 33 YEARS OLD AND LIVES IN AUSTRAILIA AND TRAVELED RECENTLY TO EUROPE HAS HAVING BLUE AND BLACK BLOTCHES ON HER LEFT ARM WHICH IS CAUSING PAIN . HER PHYSICIAN DOES NOT HAVE A CLUE AS TO WHAT IS WRONG WITH HER. HE TOLD HER THAT THE BLOOD WORK WAS NORMAL. SHE HAD A URINARY INFECTION THIS MONTH BUT NOT FROM SEX . CAN YOU RECOMMEND ANYTHING FOR HER ?"